Heat pumps
Air-to-air, air-to-water and ground-source heat pumps, including emitters, hot water, controls, sizing, installation, tariffs and standards.
Components
Heat pump and heating hardware
Air-to-air heat pumps
Fixed systems that heat and cool rooms by moving conditioned air.
Air-to-water heat pumps
Outdoor units feeding wet central heating and hot water.
Backup immersion heater
Direct-electric backup, boosting and hot-water control.
Buffer tank
Water volume, hydraulic separation, cycling and defrost support.
Domestic hot water cylinders
Stored hot water, heat-exchanger performance, sizing and safety.
Fan convector emitters
Compact hydronic emitters using fans to increase heat transfer.
Ground source heat pumps
Buried loop systems, ground arrays and borehole considerations.
Heat networks and district heating
Communal heat, district heat, HIUs and heat-pump network designs.
Hybrid heat pump systems
Heat pump plus supplementary heat source, control and eligibility.
Monobloc ASHP units
Sealed outdoor refrigerant circuit with water pipes indoors.
Open-loop GSHP
Abstraction, discharge, efficiency, maintenance and permissions.
R290 propane refrigerant
Low-GWP refrigerant benefits, flammability and siting implications.
R32 refrigerant
Common HFC refrigerant, GWP implications and servicing requirements.
Rainwater harvesting for heat pumps
Whether harvested rainwater can supply or support a water-source heat pump.
Shared ground loop systems
Shared ground arrays, individual heat pumps, ownership and regulation.
Split ASHP units
Refrigerant pipework between outdoor and indoor units.
Volumiser
Adding active heating-water volume without hydraulic separation.
Design and sizing
Heat pump design
Design flow temperature
How the design flow temperature links heat-pump output, emitter sizing and seasonal efficiency at the winter design condition.
Heat loss survey
How a room-by-room survey establishes the building fabric, ventilation and design heat load needed to size a heat-pump system.
Heat pump sizing margin
How to select a heat pump against the design load without relying on arbitrary oversizing or hidden safety factors.
MVHR interaction with heat pump heating
How mechanical ventilation with heat recovery affects ventilation heat loss, room loads and heat-pump design without removing infiltration.
Primary pipework sizing
How heat duty, design temperature drop and hydraulic resistance determine heat-pump primary pipework and pump selection.
Room-by-room heat loss
How individual room loads are calculated and used to size emitters while the building load sizes the heat pump.
SCOP performance estimate
How seasonal heat-pump efficiency is estimated, what calculation boundary it uses and why it must not be used to size the unit.
Underfloor heating compatibility
How to verify that new or existing wet underfloor heating can meet room loads at heat-pump water temperatures.
Installation
Heat pump retrofit
Commissioning flow rates
How a heat-pump water circuit is purged, balanced and proved against its design flow, temperature difference and manufacturer limits.
Condensate drainage
How an air-source heat pump's rain and defrost water is collected and discharged without ice, damp or unsafe drainage routes.
Electrical supply for heat pumps
How the circuits, protective devices, supply capacity, DNO process and certification are designed for a heat-pump system.
Outdoor unit siting
How to position an air-source heat-pump outdoor unit for airflow, noise, drainage, refrigerant safety, access and structure.
Planning constraints for ASHP
The domestic permitted-development tests for air-source heat pumps across the UK and when an application or heritage consent is needed.
Radiator emitter upgrades
How existing and replacement emitters are checked room by room for a heat pump's design temperatures and hydraulic flow.
Replacing an old boiler
How to plan the change from a boiler to a heat pump across heat loss, emitters, hot water, services, removal and handover.
Operation and maintenance
Heat pump operation
Bivalent point and hybrid switchover
How a hybrid system decides when a heat pump and supplementary heat source run alone or together.
Defrost cycle behaviour
Why an air-source heat pump defrosts, what normal behaviour looks like and which signs need investigation.
Handover settings and user controls
What a heat-pump owner should be shown, which settings should be recorded and which controls should remain installer-managed.
Hot water priority control
How a heat pump pauses or reduces space heating while it reheats a domestic hot-water cylinder.
Legionella pasteurisation cycles
How stored hot-water systems control bacterial growth and when a periodic thermal pasteurisation cycle forms part of that control.
Load compensation controls
How indoor temperature feedback adjusts a heat pump's space-heating flow temperature and how it can work with weather compensation.
Seasonal heat pump maintenance
Safe owner checks and competent servicing for air, ground and water-source heat-pump systems.
Weather compensation controls
How a heat pump adjusts space-heating flow temperature in response to outdoor conditions.
Standards and schemes
MCS and planning standards
Acoustic assessment for ASHP
The difference between an MCS 020 a) permitted development calculation, a planning noise assessment and investigation of an installed air source heat pump.
MCS 020 heat pump noise calculation
How MCS 020 a) predicts air source heat pump sound at neighbouring properties and how it fits within England's permitted development rules.
MIS 3005 heat pump standard
What MIS 3005-D and MIS 3005-I require for heat pump design, installation, commissioning and MCS certification, and how they sit alongside MCS 007, MCS 031, MCS 020 and the Boiler Upgrade Scheme.
Tariffs and grants
Grants, VAT and public schemes
Boiler Upgrade Scheme technology categories
The technology categories the Boiler Upgrade Scheme funds, the grant for each and the conditions and capacity limits that apply.
Boiler Upgrade Scheme voucher process
How a BUS grant is applied for through the installer, the customer consent step, the installation deadlines and how the money is paid.
ECO4 heating measures
Supplier-funded support for eligible low-income and vulnerable households.
Great British Insulation Scheme
Insulation support that can change heat pump readiness.
Great British Insulation Scheme vs ECO4
GBIS insulation focus compared with wider ECO4 retrofit support.
Home Energy Scotland funding
Scottish loans and grants for heat, solar and storage.
Nest Warm Homes Wales
The Welsh Government fuel poverty scheme that gives eligible households free energy advice and home energy improvements.
Zero-rated VAT on energy-saving materials
VAT treatment for installed solar, batteries, EV chargers and heat pumps.
Supplier-specific tariffs
British Gas Heat Power
British Gas Heat Power, a time-of-use electricity tariff that halves the unit rate for ten hours a day and refunds the discount as a weekly credit, covering eligibility, rates, switching, the PeakSave interaction and how it compares with other heat pump tariffs.
Cosy Octopus and Intelligent Flux
Heat pump and battery tariffs using managed operation and peak windows.
E.ON Next Pumped
Heat pump time-of-use tariff with super off-peak window.
Glossary
102 glossary terms are linked to this area, including terms shared with the other heating and cooling systems.
Browse heat pumps glossary terms